Engine idle speed governor and throttle control

ABSTRACT

An engine idle speed governor arranged in a preferred embodiment to be operated by hydraulic pressure developed by restricting the power steering pump return flow line. A hydraulic diaphragm actuator motor operates the throttle and incorporates a dashpot to provide a throttle return check operative after manual actuation of the throttle. A control unit in the power steering pump circuit incorporates the restrictive orifice as well as various valves and mechanisms to provide governor damping, limit throttle opening travel upon oil flow failure and hold a fast idle position during cold starting and warm-up.

United States Patent Brewer et al.

ENGINE IDLE SPEED GOVERNOR AND THROTTLE CONTROL Inventors: Lee M. Brewer; Robert P. Rohde,

both of Saginaw, Mich.

Assignee: General Motors Detroit, Mich.

Filed: Jan. 7, 1970 Appl. No.: 6,010

Related US. Application Data Division of Ser. No. 739,691, June 25, 1968, Pat. No.

Corporation,

US. Cl. ..236/93, 137/525, 137/614.2 Int. Cl ..F02d 31/00 Field of Search ..137/513.7, 525, 468, 614.2,

References Cited UNITED STATES PATENTS Pynchon ..l37/525 X Von Dardel et al. ..l37/525 X [151 3,705,685 [451 Dec. 12,1972

3,459,217 8/1969 Callahan ..l37/525 UX 3,463,189 8/1969 Fitzpatrick...

2,842,159 7/1958 Sprague ..l37/5l3.7

OTHER PUBLICATIONS Abstract of Application No. 164,404, 9/8/53, Kessler Primary Examiner-William E. Wayner Attorney-Robert J Outland [57] ABSTRACT An engine idle speed governor arranged in a preferred embodiment to be operated by hydraulic pressure developed by restricting the power steering pump return flow line. A hydraulic diaphragm actuator motoroperates the throttle and incorporates a dashpot to provide a throttle return check operative after manual actuation of the throttle. A control unit in the power steering pump circuit incorporates the restrictive orifice as well as various valves and mechanisms to provide governor damping, limit throttle opening travel upon oil flow failure and hold a fast idle position during cold starting and warm-up.

2 Claims, 1 Drawing IFigure ENGINE IDLE SPEED GOVERNOR AND THROTTLE CONTROL CROSS REFERENCE TO RELATED APPLICATION This application is a division of application, Ser. No. 739,691, filed June 25, 1968 now US. Pat. No. 3,537,433.

FIELD OF THE-INVENTION This invention relates to internal combustion engines DESCRIPTION OF THE PRIOR ART The provision of a throttle control to maintain engine idling speed has become of increasing importance in current automotive vehicles which may include several accessory devices, such as air conditioning systems and power steering assists, driven by the vehicle engine. The operation of these devices while the engine is idling imposes loads upon the engine which may excessively reduce its idling speed or cause it to stall. In vehi-' cles where no idle speed control is utilized, the idle speed setting must be increased to offset the loads which are imposed during operation of such accessory devices.

The use of a device to slow the closing movement of the throttle to its idle position has been known for some time. Such a device, commonly called a throttle return check, is used to prevent the excessively rapid vaporization of condensed fuel in the intake manifold which occurs when the throttle is suddenly closed. Such rapid vaporization results in a temporarily overrich mixture and may cause stalling of the engine. The throttle return check slows the closing movement of the throttle, permitting the vacuum in the intake manifold to increase gradually enough so that the vaporization of the condensed fuel occurs over a longer period and does not excessively enrich the mixture.

SUMMARY OF THE INVENTION so as to hold a relatively constant idle speed whether or 50 not various engine driven accessories are in o'peration at the time. ln addition, the governor mechanism incorporates a dash pot arrangement which acts as a throttle return check to slow closing movement of the throttle from a manually actuated open position to its idle position.

The idle speed governor is arranged to be actuated by hydraulic pressure which may be obtained from an engine accessory system, such as the power steering system. Thus, the arrangement may take advantage of the power steering pump and its connecting circuit to supply hydraulic pressure for controlling the engine idle speed.

Other features and advantages of the invention will be apparent from the following description of a preferred embodiment taken together with the accompanying drawing.

2 v BRIEF DESCRIPTION OF THE DRAWING The single FIGURE of the drawing is a partly schematic view of an internal combustion engine having an DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawing, numeral 10 generally indicates an internal combustion engine of the type commonly mounted in an automotive vehicle. Engine 10 includes a conventional carburetor 12 having a throttle member 13 for controlling the flow of airfuel mixture to the engine and consequently the engine power and speed. The. throttle member is carriedon a shaft 14 and is actuated between open and closed positions through a lever 16 which is biased in a closing direction by a spring 18 or other suitable means. A stop 20, which maybe made adjustable if desired, is provided to fix the minimum closing position of the throttle. Lever 16 may be moved in a clockwise direction to open the throttle by means of a manual linkage (not shown) which may be connected to a conventional accelerator pedal under the control of the vehicle operator. The lever 16 is also movable by idle speed governor means accord- 0 ing to the present invention, as will be subsequently described.

Engine 10 drivably connects with a hydraulic pump 22 which, in the present instance, is a power steering supply pump. Power steering pump 22 carries a supply of hydraulic fluid and is connected in a hydraulic circuit with a hydraulically actuated steering mechanism (not shown). The circuit includes a return line 24 which carries the oil from the steering mechanism back to the pump 22, passing through a control unit 26 and a connector member 28. In the idle speed range of the engine, the flow of oil produced in the circuit by the pump 22 is directly proportional to the engine speed up to a maximum flow which occurs above normal idle speed and where the pump flow is limited by an internal relief arrangement.

Control unit 26 includes a housing 29 with a passage 30 forming a part of the hydraulic circuit to the pump 22. Within passage 30 is a restrictive orifice 31 located downstream of a chamber 32 which connects with a resilient dampener valve 34. Dampener valve 34 is carried in a valve plate 36 which includes several centrally disposed openings 38 as well as a small orifice 40 located outwardly of the valve element 34. An annular 5 lip 41 of the valve 34 normally covers the openings 38 of the valve plate 36. A bimetallic valve 42 is secured as by spot welding to plate 36 in position to close the small orifice .40. The valve plate 36 is retained by a connector sleeve 44 which is held in the housing 29 of the control unit by a retaining ring 48. A dome shaped piston is reciprocably received within connector sleeve 44 and has a groove 52 along one portion of its exterior to permit the restricted passage of fluid past the piston. A spring 54 biases the piston downwardly in an open position.

Connector sleeve 44 receives one end of a hose 56 which connects control unit 26 with the housing 60 of a diaphragm-type hydraulically actuated governor motor generally indicated by numeral 62. Motor 62 sealingly retains a rolling diaphragm 64 which divides its housing 60 into two chambers 66 and 68. Chamber 66 is connected with atmospheric pressure while chamber 68 is filled with hydraulic fluid through its connection with control unit 26.

Within chamber 66 is an actuating spring 70 which acts against an annular wall 72 of the housing 60 and engages a dashpot assembly 74 so as to bias it rightwardly as shown in the drawing. Dashpot assembly 74 engages diaphragm 64 and includes within its casing 76 a movable piston 78. Piston 78 is biased rightwardly by a spring 80 acting against an annular washer 82 and engages an annular diaphragm 84 which divides the casing into two chambers 86 and 88. A retainer element 90 in the end of piston 78 retains one end ofa ball chain 92, the other end of which is retained in the tubular end 94 of a threaded connector 96 adjustably secured to throttle control lever 16. A flexible dust cover 98 engages chain 92 and one end of casing 76 to prevent the admittance of dust and other impurities into chamber 86.

In operation, throttle control lever 16 is normally actuated in a clockwise direction against the bias of spring 18 by the manual control linkage moved by the vehicle operator. Operation of the engine causes a flow of hydraulic fluid from the power steering pump 22 through the hydraulic circuit and return line 24 in the direction of the arrow and back to the power steering pump 22.

When the vehicle operator removes his foot from the accelerator, spring 18 moves lever 16 in a closing direction toward stop 20. This action is slowed by the dashpot assembly 74 which pneumatically slows the movement of piston 78 leftwardly. Since, however, spring 18 is stronger than spring 80, the throttle is slowly closed by piston 78 being moved leftwardly a sufficient distance to permit lever 16 to move to the idle position.

During normal operation, an oil pressure is built up in chamber 32 of passage 30 by the restriction by orifice 31 of the return oil flowing to the power steering pump 22. The oil pressure in the chamber 32 varies with the rate of oil flow and is conducted through orifree 40, groove 52 and hose 56 to chamber 68 of the governor motor 62 where it acts against diaphragm 64. At normal operating speeds above idle, this pressure is sufficient to move dashpot assembly 74 leftwardly against the bias of spring 70, removing the tension on chain 92 so that the governor motor does not affect the throttle position. However, under engine idle conditions, oil flow, and accordingly oil pressure, are reduced as engine speed drops, permitting rightward movement of the dashpot assembly 74 until the slack in chain 92 is taken up and the governor motor 62 begins to open the throttle and control engine speed.

The flexible lip 41 of dampener valve 34 will move away from plate 36 to permit the unrestricted passage of oil from governor motor 62 out through openings 38. This flow along with additional flow through the small orifice 40 provides for a relatively fast opening of the throttle by the governor motor. The valve 34 prevents hunting of the throttle, however, by closing ports 38 to prevent flow through them from chamber 32 into the governor motor chamber 68. Accordingly, such flow must pass through the small orifice 40. This reduces the rate of closing movements of the throttle, dampening out any tendency of the governor to hunt.

Piston 50 provides a safety feature which prevents an excessive opening of the throttle due to a failure of power steering oil pressure or an interruption of flow for any reason. In such an instance, the rapid rightward movement of dashpot assembly 74 and the consequent surge of oil against piston 50 moves it upwardly against spring 54 until it contacts the valve plate 36 stopping the movement of the piston and cutting off flow, except for leakage, through groove 52 and around the piston clearances. This prevents further rapid opening of the throttle, permitting further opening only at a very slow rate due to leakage of oil around the piston 50. In this manner, sufficient time is permitted for the correction of any temporary interruption of oil flow or for the operator to shut down the engine if a failure of power steering pressure has occurred.

When the engine is stopped, spring moves dashpot assembly 74 to its furthest rightward position, opening the throttle to a fast idle position suitable for starting the engine. When the engine is cold, it is desired to maintain this fast idle position for a period of time during warm-up. This is accomplished by the action of bimetallic valve 42 which straightens out in the cold condition, closing orifice 40 so as to restrict the passage of oil from the control unit chamber 32 into the governor motor chamber 68. Thus, the engine throttle remains in the fast idle position until increased temperature of the power steering oil causes movement of the bimetallic valve 42 away from the orifice 40. This permits oil to slowly move into chamber 68, eventually causing the throttle to close to the normal idling position.

While the invention has been described by reference to a preferred embodiment chosen for purposes of illustration, it should be apparent that numerous changes could be made within the spirit of the inventive concepts set forth. Accordingly, it is desired that the invention not be limited by the embodiment disclosed, but that it be given the scope defined by the language of the following claims.

We claim:

1. A control unit for a hydraulic engine idle speed governor and comprising a housing,

first fluid passage means through said housing and adapted to be connected in a hydraulic circuit,

a restricted orifice in said passage means,

second fluid passage means in said housing and connecting with said first passage means adjacent said a valve plate across said second passage means and having a plurality of openings to permit fluid flow through said second passage means,

a resilient dampener valve supported by said valve plate and arranged to prevent flow through a first set of said openings in a direction away from said first passage means and to permit free flow through said first openings in the opposite direction, and

a reciprocable piston movable in said second fluid passage means and biased into a position permitting limited flow of fluid in one direction through said second passage means, said piston being movable through a limited travel, to permit a predetermined volume of free fluid flow in the other direction, and into a position restricting 5 further fluid flow in said other direction.

2. The control unit of claim 1 and further comprising bimetallic temperature responsive valve means in said 

1. A control unit for a hydraulic engine idle speed governor and comprising a housing, first fluid passage means through said housing and adapted to be connected in a hydraulic circuit, a restricted orifice in said passage means, second fluid passage means in said housing and connecting with said first passage means adjacent said orifice, a valve plate across said second passage means and having a plurality of openings to permit fluid flow through said second passage means, a resilient dampener valve supported by said valve plate and arranged to prevent flow through a first set of said openings in a direction away from said first passage means and to permit free flow through said first openings in the opposite direction, and a reciprocable piston movable in said second fluid passage means and biased into a position permitting limited flow of fluid in one direction through said second passage means, said piston being movable through a limited travel, to permit a predetermined volume of free fluid flow in the other direction, and into a position restricting further fluid flow in said other direction.
 2. The control unit of claim 1 and further comprising bimetallic temperature responsive valve means in said housing and cooperating with said valve plate to block a second set of said openings under cold temperatures but to permit flow through said second openings in response to increased fluid temperatures. 